The use of gas discharge lamps, such as high intensity discharge (HID) lamps, is common in a wide variety of applications. A gas discharge lamp operates in a fundamentally different way than an incandescent lamp, and therefore may not be directly connectable to existing lighting fixtures designed for incandescent lamps. To allow use of a gas discharge lamp with existing lighting fixtures, integrally ballasted gas discharge lamp assemblies have been developed. In an integrally ballasted lamp assembly, a ballast circuit is provided within the lamp housing and the lamp housing is configured to directly connect to existing lighting fixtures. In general, the ballast circuit receives an electrical input, e.g. an alternating current (A.C.) or direct current (D.C.) input, from the existing lighting fixture and provides a stable output to the gas discharge lamp.
One example of a known integrally ballasted lamp assembly 100 is illustrated in FIG. 1. In the embodiment shown in FIG. 1, the assembly includes a screw shell 102, a housing 104, a heat sink/EMI shield 106, a printed circuit board (PCB) with a ballast circuit thereon 108, a lamp receptacle 110, connector clips 112,114, a glass reflector 116, a gas discharge lamp 118, a support disk 120 and a lens 122. In general, the PCB with the ballast circuit thereon 108 is provided within the housing 104 and is electrically connected to the screw shell 102, which is sometimes referred to as an Edison connector. The screw shell is configured to be received within an existing light fixture through threaded engagement of the threads on the screw shell with corresponding threads on the existing lighting fixture. An electrical input is thereby coupled from the lighting fixture to the ballast circuit on the PCB through the screw shell.
The heat sink/EMI shield 106 may be provided in first and second parts that are fastened around the PCB 108 and mechanically coupled thereto. Heat generated by the ballast circuit during operation is dissipated by the heat sink/EMI shield 106. The heat sink/EMI shield also provides shielding of electro-magnetic interference (EMI) from the ballast circuit on the PCB.
The lamp receptacle 110 may include a bottom portion having connector clip openings therein. The connector clips 112, 114 are inserted into the connector clip openings and secured to the bottom of the lamp receptacle in a snap-fit manner so that a portion of the connector clips extends outwardly from the bottom of the lamp receptacle. The PCB 108 is positioned adjacent to the bottom of the lamp receptacle and the connector clips each make a spring contact with an associated contact on the PCB board 108. This provides an electrical connection from contacts on the PCB board to each of the connector clips.
The glass reflector 116 has a bottom portion disposed in an open end of the lamp receptacle 110 and is mechanically supported by the lamp receptacle. A bottom portion of the lamp 118 extends through a through-passage in the reflector 116 and into the lamp receptacle 110. The electrical leads of the lamp extend through the connector clip openings in the bottom of the lamp receptacle and in contact with the respective connector clips 112,114. The lamp leads may then be welded to the respective connector clips to make an electrical connection between the lamp leads and contacts on the PCB board through the connector clips that are snap fit to the bottom of the lamp receptacle.
To complete the assembly, the open end of the reflector 116 may be closed by the lens 122, e.g. using a bezel, and the top of the lamp 118 may be supported against the interior surface of the reflector by the support disk 120. One example of an integrally ballasted lamp similar to that shown in FIG. 1 is shown and described in U.S. Patent Application Publication No. US 2009/0279310, the teachings of which are hereby incorporated herein by reference. Other reflector lamp configurations are known, for example, from U.S. Pat. Nos. 7,227,308, 6,162,096, 5,751,095, 5,629,581, 5,272,409 and 5,057,735 and U.S. Patent Application Publication Nos. 2005/0213332 and 2004/0120148.